SE 456,261 discloses such a known beam construction. This beam construction has first and second horizontally arranged beams, which are joined perpendicularly to each other, thereby forming a frame where the first and second beams are joined in T- or X-shaped joints. The frame is suspended from the ceiling in a surrounding room and is used to support filter elements and blank panels which define the clean room below the clean room ceiling. Also other equipment such as sprinkler nozzles, lighting fittings and airflow-guiding sheets can be fixed in the frame or suspended therefrom. The first and the second beams have on their upper sides longitudinal ducts for receiving a liquid or viscous gel acting as sealant. The ducts are formed of a space, which is formed between a web portion, an axially extending projection and, opposing the projection, an edge portion of the first and second beams. The beams are of symmetrical cross-section and have two such longitudinal ducts, one on each side of a vertical symmetry line of the cross-section.
The filter elements and the blank panels are, along their edges, provided with knives, which after mounting on the frame penetrate into the sealant in the ducts. This results in a ceiling construction which is completely tight from the viewpoint of contamination.